The present invention refers to a system and to a method for detecting the presence of antifreezing residues in a hermetic compressor, which has been removed from a refrigeration circuit.
The presence of water in the circuit of a refrigeration system comprising a hermetic compressor may cause failure in the refrigeration system, due to clogs in the capillary tube of said system caused by the freezing of water inside this tube. The existence of water in the system results, for instance, when vacuum is not used for drying and eliminating the non-condensable substances from the refrigeration circuit before introducing the refrigerant fluid in said circuit.
In order to avoid failures in the system due to freezing, some technicians introduce in the refrigeration circuit an antifreezing fluid, among which the alcohols are the most common, although antifreezing substances in the form of ketones are also used. Among the ketones most used as an antifreezing substance is propanone (acetone). Other well known antifreezing substances are ammonia, inorganic salts, organic and inorganic acids, glicols, ethers, etc.
Though being able to allow the free flow of refrigerant fluid in the refrigeration circuit, the antifreezing substances are prejudicial to the refrigeration system, since they cause damages to the components of the compressor, leading to failure of the latter.
Several techniques are known for detecting antifreezing substances in compressors. Nevertheless, the application of these techniques require sophisticated and costly equipments, which are only available in large laboratories. Moreover, such techniques take a long time and further require that the compressor itself or a sample of its lubricant oil be transported to the laboratories provided with said equipments.
In function of the difficulty for detecting, in a practical, quick and safe manner, the presence of these antifreezing substances in the internal environment of the compressor, mainly due to the fact that said compressor has been opened and therefore a large part of its internal atmosphere carrying the antifreezing substance has dissipated to the environment, one cannot say that the operative failures of the compressor result from the undue utilization of the antifreezing substances.
This difficulty in detecting the presence of antifreezing substances in the compressor make the manufacturers substitute the compressors when an operative failure occurs during the guaranty period of said compressors.
Thus, it is an object of the present invention to provide a system and a method for detecting antifreezing substances in a compressor which has been removed from a refrigeration circuit, which allows to determine the presence of residues of antifreezing substances inside the compressor shell in a safe and unquestionable way.
A more specific object of the present invention is to provide a system and a method for the safe detection of antifreezing substances in a compressor, which is easy and practical to carry out and which may be achieved away from the operation site of the refrigeration system to which the compressor was connected, such as in a test installation.
The objectives mentioned above are achieved through a system for detecting antifreezing substances in a hermetic compressor, which has been removed from a refrigeration circuit and which comprises a hermetic shell having at least one nozzle, which communicates the inside of said shell with the environment and which comprises an antifreezing substance detecting means, containing at least one reactant, which is contactable with the atmosphere inside the shell through the nozzle, said antifreezing substance detecting means showing an alteration which is detectable when contacted by a determined amount of said antifreezing substance during a determined time interval, within which the determined amount of the antifreezing substance existing in the hermetic shell is able to cause the detectable alteration of the antifreezing substance detecting means.
The method for detecting the antifreezing substances in the system generally includes the following steps: connecting, to said nozzle, an antifreezing substance detecting means containing at least one reactant which will show a detectable alteration when contacted by a determined amount of said antifreezing substance; and contacting said antifreezing substance detecting means with the internal atmosphere of the compressor through the nozzle during a determined time interval, within which a determined amount of the antifreezing substance existing in the hermetic shell will cause the detectable alteration of the antifreezing substance detecting means.